A PES (Photoelectron Spectroscopy) graph is a plot that shows the energy levels of electrons in an atom or molecule. It displays the energy required to remove each electron from the atom or molecule.
Related terms
Electron Configuration: The arrangement of electrons in an atom's orbitals.
Ionization Energy: The energy required to remove an electron from an atom or ion.
Valence Electrons: The electrons located in the outermost shell (valence shell) of an atom.